Clinical depression presents with symptoms at a number of levels, including decreased cognitive and behavioral arousal (psychomotor retardation), a loss of interest in pleasurable activities (anhedonia), a blunting of emotional expressivity (depressed affect), and a distortion of memory and expectancy for personally-relevant life events (depressive cognitive bias). Research is required to explain how the depressive response impairs neuropsychological function at multiple levels of the neuraxis. In previous research, the investigator used electrophysiological and cognitive measures to show that a depressed mood preferentially impairs the right hemisphere's attentional function, providing a theoretical model that may help explain arousal, attention, memory and affective experience. In the present research, the investigator extends this work with improved behavioral paradigms, with dense sensor array measures of brain electrical activity, and with clinical recruitment and evaluation procedures that target melancholic depression. The combination of these electrophysiologic and cognitive measures may provide new insight into the mechanisms of positive arousal (depression-elation), negative arousal (calmness-anxiety), and how they modulate the memory operations of corticolimbic networks. The specific measurement of spatial memory skills will test the theoretical model that positive arousal is particularly important to the dorsal corticolimbic pathway which is integral not only to spatial memory but to the right hemisphere's role in affective communication and cognition. More generally, the integration of neurophysiological with cognitive studies may help bridge the gap between biological and psychological approaches to depression.